US President Donald Trump's administration is asking states to speed delivery of COVID-19 vaccines to people 65 and older and to others at high risk by no longer holding back the second dose of the two-dose shots, officials say.
Health and Human Services Secretary Alex Azar said that "the administration in the states has been too narrowly focused".
As a result, he said, the Trump administration is now asking states to vaccinate people age 65 and over and those under 65 with underlying health conditions that put them at high risk.
He said the vaccine production is such that the second dose of the two-shot vaccine can be released without jeopardising immunisation for those who got the first shot.
"We now believe that our manufacturing is predictable enough that we can ensure second doses are available for people from ongoing production," Azar told ABC's Good Morning America.
"So everything is now available to our states and our health care providers."
Each state has its own plan for who should be vaccinated, based on recommendations from the federal Centers for Disease Control and Prevention.
The CDC recommendations give first priority to health care workers and nursing home residents.
But the slow pace of the vaccine rollout has frustrated many people in the US at a time when the coronavirus death toll has continued to rise.
More than 376,000 people have died, according to the Johns Hopkins database.
Azar said it was now time to move "to the next phase on the vaccine program" and expand the pool of those eligible to get the first dose.
That also means expanding the number of places where people can be vaccinated by adding community health centers and additional drug stores.